An MxN Young tableau is an MxN matrix such that the entries of each row are in sorted order from left to right and the entries of each column are in sorted order from top to bottom. Some of the entries of a Young tableau may be infinity, which we treat as nonexistent elements. Thus, a Young tableau can be used to hold r <= mn finite numbers.
How to find an O(M+N) — time algorithm to determine whether a given number is stored in a given MxN Young tableau?
(source : Introduction to Algorithms)